I can add that the same thing happens before the first encounter with Mystira. That is, if you get trapped by tentacles during the first passage through the Deserted Base and do not resist, the protagonist is freed without a fight, but his image disappears.
This error does not occur if the protagonist gets trapped already having meat parasites on his body. Just in case, I checked what happens in version 70.1 - this bug does not exist there.